Film cartridges loaded into cameras are often mechanically held within a chamber to insure the film cartridge does not fall out of the camera inadvertently. This is particularly true with bottom-loading cameras. A problem that can occur with such bottom-loading cameras is that after a film cartridge has been loaded in the camera, a user may decide to load a different film cartridge rather than use the one just loaded. However, the already-loaded film cartridge typically cannot be unloaded without closing the chamber door and cycling the film through the camera. In some cameras, the camera operator might even be required to expose some film before being able to rewind and unload the undesired film cartridge. Therefore, it is desirable to have the ability to eject a film cartridge from a bottom or top loading camera (axial load) prior to camera initialization or closing of the chamber door.
The door release of a camera typically opens a latch or otherwise allows a chamber door to open so that a film cartridge can be loaded or unloaded from the camera. Cameras can have several different mechanisms, such as camera initialization, whose operation is related to the closing of the chamber door. For example, some film cartridges include a light-lock door which when closed prevents inappropriate exposure of unexposed film. After a film cartridge has been loaded into a camera and the film door is closed, the camera needs to open the light lock door before film can be thrust from the film cartridge. When the user decides to rewind the film and eject the film cartridge, the camera must close the light lock door prior to opening the film door.(see e.g. U.S. Pat. No. 5,231,438 which is incorporated herein by reference (the '438 patent)).
A camera light lock drive mechanism opens and closes the light lock door. The light lock drive mechanism could include gears, but they do not lend themselves to intermittent motion and, in addition, are relatively complex to design and manufacture. It is therefore desirable to have a light lock drive mechanism that requires less design cost and is less complex, thus providing a higher reliability, lower cost camera to the user.
Another mechanism related to the chamber door is a film cartridge ejector for ejecting a film cartridge from the camera chamber. One method of cartridge ejection, disclosed in the above-cited cross-referenced U.S. Pat. No. 5,530,504, uses an independent trigger mechanism that initiates cartridge ejection when the film door is opened. This cartridge ejection trigger method however places large forces upon the film door, causing many mechanical and operational problems including difficulty in closing the film door and warping the film door.
In an effort to reduce the forces applied to the film door and also to reduce the parts count in a camera, it would be desirable to operate the cartridge light-lock door and cartridge ejection trigger with mechanisms that do not involve the film door.